#pragma region License
/*
MIT License
Copyright © 2006 The Mono.Xna Team

All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#pragma endregion License

#ifndef Curve_h
#define Curve_h


#include <System/RObject.h>
#include <System/RString.h>
#include <System/RArray.h>
#include <System/IEquatable.h>

#include "RMathHelper.h"

namespace Riccsson
{
	namespace Xna
	{
		namespace Framework
		{
			class Curve
			{
				#pragma region private: Fields

				private: GC_PTR<CurveKeyCollection> keys;
				private: CurveLoopType postLoop;
				private: CurveLoopType preLoop;

				#pragma endregion private: Fields


				#pragma region public: Properties

				public: PROP3_GET(bool, IsConstant)
				{
					return this->keys.Count <= 1;
				}

				public: PROP3_GET(GC_PTR<CurveKeyCollection>, Keys)
				{
					return this->keys;
				}

				public: PROP3_GET(CurveLoopType, PostLoop)
				{
					return this->postLoop;
				}
				public: PROP3_SET(CurveLoopType, PostLoop)
				{
					this->postLoop = value;
				}

				public: PROP3_GET(CCurveLoopType, PreLoop)
				{
					return this->preLoop;
				}
				public: PROP3_SET(CCurveLoopType, PreLoop)
				{
					this->preLoop = value;
				}

				#pragma endregion public: Properties


				#pragma region public: Constructors

				public: Curve()
				{
					this->keys = new CurveKeyCollection();
				}

				#pragma endregion public: Constructors


				#pragma region public: Methods

				public: GC_PTR<Curve> Clone()
				{
					GC_PTR<Curve> curve = new Curve();

					curve->keys = this->keys.Clone();
					curve->preLoop = this->preLoop;
					curve->postLoop = this->postLoop;

					return curve;
				}

				public: float Evaluate(float position)
				{
					CurveKey* first = (*keys)[0];
					CurveKey* last = (*keys)[keys->Count - 1];

					if (position < first->Position)
					{
						switch (this->PreLoop)
						{
							case CurveLoopType::Constant:
								//constant
								return first->Value;

							case CurveLoopType::Linear:
								// linear y = a*x +b with a tangeant of last point
								return first->Value - first->TangentIn * (first->Position - position);

							case CurveLoopType::Cycle:
								//start -> end / start -> end
								int cycle = GetNumberOfCycle(position);
								float virtualPos = position - (cycle * (last->Position - first->Position));
								return GetCurvePosition(virtualPos);

							case CurveLoopType::CycleOffset:
								//make the curve continue (with no step) so must up the curve each cycle of delta(value)
								cycle = GetNumberOfCycle(position);
								virtualPos = position - (cycle * (last->Position - first->Position));
								return (GetCurvePosition(virtualPos) + cycle * (last->Value - first->Value));

							case CurveLoopType::Oscillate:
								//go back on curve from end and target start 
								// start-> end / end -> start
								cycle = GetNumberOfCycle(position);
								if (0 == cycle % 2f)//if pair
									virtualPos = position - (cycle * (last->Position - first->Position));
								else
									virtualPos = last->Position - position + first->Position + (cycle * (last.Position - first.Position));
								return GetCurvePosition(virtualPos);
						}
					}
					else if (position > last->Position)
					{
						int cycle;
						switch (this->PostLoop)
						{
							case CurveLoopType::Constant:
								//constant
								return last->Value;

							case CurveLoopType::Linear:
								// linear y = a*x +b with a tangeant of last point
								return last->Value + first->TangentOut * (position - last->Position);

							case CurveLoopType::Cycle:
								//start -> end / start -> end
								cycle = GetNumberOfCycle(position);
								float virtualPos = position - (cycle * (last->Position - first->Position));
								return GetCurvePosition(virtualPos);

							case CurveLoopType::CycleOffset:
								//make the curve continue (with no step) so must up the curve each cycle of delta(value)
								cycle = GetNumberOfCycle(position);
								virtualPos = position - (cycle * (last->Position - first->Position));
								return (GetCurvePosition(virtualPos) + cycle * (last->Value - first->Value));

							case CurveLoopType::Oscillate:
								//go back on curve from end and target start 
								// start-> end / end -> start
								cycle = GetNumberOfCycle(position);
								virtualPos = position - (cycle * (last->Position - first->Position));
								if (0 == cycle % 2f)//if pair
									virtualPos = position - (cycle * (last->Position - first->Position));
								else
									virtualPos = last->Position - position + first->Position + (cycle * (last.Position - first.Position));
								return GetCurvePosition(virtualPos);
						}
					}

					//in curve
					return GetCurvePosition(position);
				}

				public: void ComputeTangents (CurveTangent tangentType )
				{
					ComputeTangents(tangentType, tangentType);
				}
				
				public: void ComputeTangents(CurveTangent tangentInType, CurveTangent tangentOutType)
				{
					for (var i = 0; i < Keys->Count; i++)
						ComputeTangent(i, tangentInType, tangentOutType);
				}

				public: void ComputeTangent(int keyIndex, CurveTangent tangentType)
				{
					ComputeTangent(keyIndex, tangentType, tangentType);
				}

				public: void ComputeTangent(int keyIndex, CurveTangent tangentInType, CurveTangent tangentOutType)
				{
					// See http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.curvetangent.aspx

					var key = (*keys)[keyIndex];

					float p0, p, p1;
					p0 = p = p1 = key.Position;

					float v0, v, v1;
					v0 = v = v1 = key.Value;

					if ( keyIndex > 0 )
					{
						p0 = (*keys)[keyIndex - 1].Position;
						v0 = (*keys)[keyIndex - 1].Value;
					}

					if (keyIndex < keys.Count-1)
					{
						p1 = (*keys)[keyIndex + 1].Position;
						v1 = (*keys)[keyIndex + 1].Value;
					}

					switch (tangentInType)
					{
						case CurveTangent::Flat:
							key->TangentIn = 0;
							break;
						case CurveTangent::Linear:
							key->TangentIn = v - v0;
							break;
						case CurveTangent::Smooth:
							var pn = p1 - p0;
							if (Math::Abs(pn) < float.Epsilon)
								key->TangentIn = 0;
							else
								key->TangentIn = (v1 - v0) * ((p - p0) / pn);
							break;
					}

					switch (tangentOutType)
					{
						case CurveTangent::Flat:
							key->TangentOut = 0;
							break;
						case CurveTangent::Linear:
							key->TangentOut = v1 - v;
							break;
						case CurveTangent::Smooth:
							var pn = p1 - p0;
							if (Math::Abs(pn) < float.Epsilon)
								key->TangentOut = 0;
							else
								key->TangentOut = (v1 - v0) * ((p1 - p) / pn);
							break;
					}
				}

				#pragma endregion public: Methods


				#pragma region private: Methods

				private: int GetNumberOfCycle(float position)
				{
					float cycle = (position - keys[0].Position) / (keys[keys.Count - 1].Position - keys[0].Position);
					if (cycle < 0f)
						cycle--;
					return (int)cycle;
				}

				private: float GetCurvePosition(float position)
				{
					//only for position in curve
					CurveKey* prev = (*this->keys)[0];
					CurveKey* next;
					for (int i = 1; i < this->keys.Count; i++)
					{
						next = (*this->Keys)[i];
						if (next->Position >= position)
						{
							if (prev->Continuity == CurveContinuity.Step)
							{
								if (position >= 1f)
								{
									return next->Value;
								}
								return prev->Value;
							}
							float t = (position - prev->Position) / (next->Position - prev->Position);//to have t in [0,1]
							float ts = t * t;
							float tss = ts * t;
							//After a lot of search on internet I have found all about spline function
							// and bezier (phi'sss ancien) but finaly use hermite curve 
							//http://en.wikipedia.org/wiki/Cubic_Hermite_spline
							//P(t) = (2*t^3 - 3t^2 + 1)*P0 + (t^3 - 2t^2 + t)m0 + (-2t^3 + 3t^2)P1 + (t^3-t^2)m1
							//with P0.value = prev->value , m0 = prev->tangentOut, P1= next->value, m1 = next->TangentIn
							return (2 * tss - 3 * ts + 1f) * prev->Value + (tss - 2 * ts + t) * prev->TangentOut + (3 * ts - 2 * tss) * next->Value + (tss - ts) * next->TangentIn;
						}
						prev = next;
					}
					return 0f;
				}

				#endregion
			};
		}
	}
}

#endif